Asphalt mat insulation

Brands

Dynamat regular

Fatmat

Peel n stick

Info

Asphalt mats are primarily sound deadeners – they’re affixed to the center of body panels to increase mass and absorb vibration. They’re made of asphalt-impregnated rubber (butyl or styrene-butadiene) and are essentially roofing material! They provide great sound insulation, and probably thermal insulation as well, but with significant downsides:

odor – on a hot day, these are known to smell like hot asphalt (because that’s exactly what they are!)

loss of adhesion – again in the heat, the panels can melt and sag, ending up in a goopy asphalt mess at the bottom of your door or wall panel

The sounddeadenershowdown.com site again has good information about this material. I think a good recommendation would be to avoid it; if you decide to use it, do so in combination with another material. These aren’t meant as all-over insulation, but instead as strategically-placed sound deadener.